Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsIntegrated Circuits (ICs)Timer IC t- real time clock Clock/calendar SOIC 8 N

C RTC with Trickle Charger

DS1340

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1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.

General Description

The DS1340 is a real-time clock (RTC)/calendar that is

pin compatible and functionally equivalent to the ST

M41T00, including the software clock calibration. The

device additionally provides trickle-charge capability

on the V

BACKUP

pin, a lower timekeeping voltage, and

an oscillator STOP flag. Block access of the register

map is identical to the ST device. Two additional regis-

ters, which are accessed individually, are required for

the trickle charger and flag. The clock/calendar pro-

vides seconds, minutes, hours, day, date, month, and

year information. A built-in power-sense circuit detects

power failures and automatically switches to the back-

up supply. Reads and writes are inhibited while the

clock continues to run. The device is programmed seri-

ally through an I

C bidirectional bus.

Applications

Portable Instruments

Point-of-Sale Equipment

Medical Equipment

Telecommunications

Features

♦ Enhanced Second Source for the ST M41T00

♦ Available in a Surface-Mount Package with an

Integrated Crystal (DS1340C)

♦ Fast (400kHz) I

C Interface

♦ Software Clock Calibration

♦ RTC Counts Seconds, Minutes, Hours, Day, Date,

Month, and Year

♦ Automatic Power-Fail Detect and Switch Circuitry

♦ Trickle-Charge Capability

♦ Low Timekeeping Voltage Down to 1.3V

♦ Three Operating Voltage Ranges (1.8V, 3V, and 3.3V)

♦ Oscillator Stop Flag

♦ Available in 8-Pin µSOP or SO Packages

♦ Underwriters Laboratories (UL) Recognized

Ordering Information

CPU

SDA

SCL

GND

X2X1

CRYSTAL

FT/OUT

BACKUP

= t

/ C

DS1340

Typical Operating Circuit

PART TEMP RANGE

PIN-

PACKAGE

TOP MARK

†

DS1340Z-18+ -40°C to +85°C

8 SO

(0.150in)

D1340-18

DS1340Z-3+ -40°C to +85°C

8 SO

(0.150in)

DS1340-3

DS1340Z-33+ -40°C to +85°C

8 SO

(0.150in)

D134033

DS1340U-18+ -40°C to +85°C 8 μSOP 1340 -18

DS1340U-3+ -40°C to +85°C 8 μSOP 1340 -3

DS1340U-33+ -40°C to +85°C 8 μSOP 1340 -33

DS1340C-18# -40°C to +85°C 16 SO DS1340C-18

DS1340C-3# -40°C to +85°C 16 SO DS1340C-3

DS1340C-33# -40°C to +85°C 16 SO DS1340C-33

Pin Configurations appear at end of data sheet.

Denotes a lead(Pb)-free/RoHS-compliant package.

Denotes a RoHS-compliant device that may include lead(Pb)

that is exempt under RoHS requirements. The lead finish is

JESD97 category e3, and is compatible with both lead-based

and lead-free soldering processes.

†

A "+" anywhere on the top mark denotes a lead(Pb)-free device.

A "#" denotes a RoHS-compliant device.

19-5578; Rev 8; 4/13

Summary of content (16 pages)

PAGE 1
DS1340 I2C RTC with Trickle Charger General Description Features The DS1340 is a real-time clock (RTC)/calendar that is pin compatible and functionally equivalent to the ST M41T00, including the software clock calibration. The device additionally provides trickle-charge capability on the VBACKUP pin, a lower timekeeping voltage, and an oscillator STOP flag. Block access of the register map is identical to the ST device.
PAGE 2
DS1340 I2C RTC with Trickle Charger ABSOLUTE MAXIMUM RATINGS Operating Temperature Range ...........................-40°C to +85°C Storage Temperature Range .............................-55°C to +125°C Lead Temperature (soldering, 10s) .................................+260°C Soldering Temperature (reflow) .......................................+260°C Voltage Range on VCC or VBACKUP Pins Relative to Ground.............................................-0.3V to +6.
PAGE 3
DS1340 I2C RTC with Trickle Charger DC ELECTRICAL CHARACTERISTICS (VCC = 0V, VBACKUP = 3.7V, TA = -40°C to +85°C, unless otherwise noted.) (Note 1) PARAMETER VBACKUP Current VBACKUP Data-Retention Current SYMBOL CONDITIONS MIN TYP MAX UNITS IBACKUP1 OSC ON, FT = 0 (Note 9) 800 1150 IBACKUP2 OSC ON, FT = 1 (Note 9) 850 1250 IBACKUP3 OSC ON, FT = 0, VBACKUP = 3.0V, TA = +25°C (Notes 9, 10) 800 1000 25.
PAGE 4
DS1340 I2C RTC with Trickle Charger POWER-UP/POWER-DOWN CHARACTERISTICS (TA = -40°C to +85°C) (Figure 2) PARAMETER SYMBOL CONDITIONS MIN TYP (Note 17) MAX UNITS 2 ms Recovery at Power-Up tREC VCC Fall Time; VPF(MAX) to VPF(MIN) tVCCF 300 µs VCC Rise Time; VPF(MIN) to VPF(MAX) tVCCR 0 µs WARNING: Under no circumstances are negative undershoots, of any amplitude, allowed when device is in battery-backup mode.
PAGE 5
DS1340 I2C RTC with Trickle Charger VCC VPF(MAX) VPF VPF(MIN) VPF tR tF tREC INPUTS RECOGNIZED DON'T CARE RECOGNIZED HIGH-Z OUTPUTS VALID VALID Figure 2. Power-Up/Power-Down Timing Typical Operating Characteristics (VCC = +3.3V, TA = +25°C, unless otherwise noted.) 100 800 -3.3V SUPPLY CURRENT (nA) 150 850 DS1340 toc02 DS1340 toc01 125 SUPPLY CURRENT (μA) SUPPLY CURRENT (μA) 200 IBACKUP1 (FT = 0) vs. VBACKUP ICCS vs. VCC FT = 0 150 100 -3.0V 75 DS1340 toc03 ICCSA vs.
PAGE 6
DS1340 I2C RTC with Trickle Charger Pin Description PIN NAME 8 16 1 — X1 2 — X2 FUNCTION Connections for a Standard 32.768kHz Quartz Crystal. The internal oscillator circuitry is designed for operation with a crystal having a specified load capacitance (CL) of 12.5pF. X1 is the input to the oscillator and can optionally be connected to an external 32.768kHz oscillator. The output of the internal oscillator, X2, is left unconnected if an external oscillator is connected to X1.
PAGE 7
DS1340 I2C RTC with Trickle Charger when VCC drops below VBACKUP. The registers are maintained from the V BACKUP source until V CC is returned to nominal levels (Table 1). After VCC returns above VPF, read and write access is allowed tREC. the crystal and oscillator from noise. Refer to Application Note 58: Crystal Considerations with Dallas Real-Time Clocks (www.maximintegrated.com/RTCapps) for detailed information. Oscillator Circuit DS1340C Only The DS1340 uses an external 32.768kHz crystal.
PAGE 8
DS1340 I2C RTC with Trickle Charger X1 FT/OUT CL CL X2 512Hz 32,768Hz MUX/ BUFFER DIVIDER AND CALIBRATION CIRCUIT "C" VERSION ONLY 1Hz VCC CLOCK AND CALENDAR REGISTERS POWER CONTROL VBACKUP N CONTROL LOGIC SERIAL INTERFACE AND ADDRESS REGISTER SCL SDA USER BUFFER (7 BYTES) DS1340 Figure 5. Functional Diagram Address Map Table 3 shows the DS1340 address map. The RTC registers are located in address locations 00h to 06h, and the control register is located at 07h.
PAGE 9
DS1340 I2C RTC with Trickle Charger register increments at midnight. Values that correspond to the day of week are user-defined but must be sequential (i.e., if 1 equals Sunday, then 2 equals Monday, and so on). Illogical time and date entries result in undefined operation. Bit 7 of register 0 is the enable oscillator (EOSC) bit. When this bit is set to 1, the oscillator is disabled. When cleared to 0, the oscillator is enabled. The initial power-up value of EOSC is 0.
PAGE 10
DS1340 I2C RTC with Trickle Charger Table 4.
PAGE 11
DS1340 I2C RTC with Trickle Charger have a one-second interval where the calibration is performed. Negative calibration blanks 128 cycles of the 32,768Hz oscillator, slowing the clock down. Positive calibration inserts 256 cycles of the 32,768Hz oscillator, speeding the clock up. If a binary 1 is loaded into the calibration bits, only the first two minutes in the 64minute cycle are modified. If a binary 6 is loaded, the first 12 minutes are affected, and so on.
PAGE 12
DS1340 I2C RTC with Trickle Charger determined by the master device. The information is transferred byte-wise and each receiver acknowledges with a ninth bit. Acknowledge: Each receiving device, when addressed, is obliged to generate an acknowledge after the reception of each byte. The master device must generate an extra clock pulse that is associated with this acknowledge bit.
PAGE 13
DS1340 I2C RTC with Trickle Charger S 1101000 0 A XXXXXXXX A XXXXXXXX S - START MASTER TO SLAVE A - ACKNOWLEDGE (ACK) P - STOP R/W - READ/WRITE OR DIRECTION BIT ADDRESS A XXXXXXXX A ... XXXXXXXX A P A P SLAVE TO MASTER DATA TRANSFERRED (X + 1 BYTES + ACKNOWLEDGE) Figure 8.
PAGE 14
DS1340 I2C RTC with Trickle Charger Handling, PC Board Layout, and Assembly The DS1340C package contains a quartz tuning-fork crystal. Pick-and-place equipment may be used, but precautions should be taken to ensure that excessive shocks are avoided. Exposure to reflow is limited to 2 times maximum. Ultrasonic cleaning should be avoided to prevent damage to the crystal. Avoid running signal traces under the package, unless a ground plane is placed between the package and the signal line. All N.C.
PAGE 15
DS1340 I2C RTC with Trickle Charger Revision History REVISION NUMBER REVISION DATE 0 6/03 1 2 3 4 5 Maxim Integrated 7/04 12/04 11/05 3/06 8/08 DESCRIPTION PAGES CHANGED Initial release. — Changed “2-wire” to “I2C” throughout the data sheet. All Added UL recognition info bullet to the Features section and to the VBACKUP pin description. 1, 6 Added the “I/O Capacitance (SCL, SDA)” parameter (CI/O) to the AC Electrical Characteristics table.
PAGE 16
DS1340 I2C RTC with Trickle Charger Revision History (continued) REVISION NUMBER 6 REVISION DATE 10/10 DESCRIPTION PAGES CHANGED Updated the top mark information in the Ordering Information table. 1 Updated the soldering information in the Absolute Maximum Ratings section. 2 Updated the SDA and SCL pin descriptions in the Pin Description table. 6 Increased ESR from 45,60k (max) to 80k (max) in Table 2. 7 Updated the Package Information table.